1. Field of the Invention
The present invention generally relates to a video signal recording/reproducing apparatus. More specifically, the present invention relates to a video signal recording/reproducing apparatus such as a video tape recorder adapted for recording an audio signal to be multiplexed as well as a video signal in a recording medium.
2. Description of the Prior Art
A video tape recorder of a type adapted for recording an audio signal to be multiplexed included in a television signal in an audio track of a video tape and for reproducing the audio signal therefrom has already been proposed. Such proposed video tape recorder is structured such that a multiplexed audio signal included in a transmitted television signal is applied to a decoder, where audio signals of two channels are obtained, and then these audio signals are recorded in two separate audio tracks. The audio signals of two channels constitute a left and right signals, a main and auxiliary signals or the same monaural signals, depending on a stereo mode, a bilingual mode, or a monaural mode, respectively. A conventional video tape recorder of this type has neither a function of discriminating the kinds of multiplexing of an audio signal, such as a stereo mode, a bilingual mode or a monaural mode, recorded on an audio track, nor a function of encoding a reproduced audio signal into a multiplexed audio signal for a television receiver. Therefore, the audio signals of two channels reproduced from a video tape are merely utilized in such a manner as to drive speakers included in a television receiver directly, i.e. without interposition of any particular signal converting circuit, rather than utilized by being supplied from an antenna input to a television receiver. Thus, in the case where speakers of a television receiver are directly driven from a video tape recorder, the signals need not pass through an encoder in a video tape recorder and a signal converting circuit in a television receiver and for this reason chances of degradation of an audio signal can be accordingly decreased; however, this is not necessarily advantageous in consideration of a general connection manner nowadays of a video tape recorder and a television receiver. More specifically, since a video tape recorder and a television receiver are generally connected through an antenna terminal, a supply of an audio signal not by an antenna terminal means that no audio signal can be transferred from a video tape recorder to a television receiver having no input terminal for such audio signal. Even if a television receiver comprises an audio signal input terminal, a video signal input terminal for a single video signal and two audio signal input terminals and signal lines for connection to these terminals need be provided, which makes tiresome connection of a video tape recorder with a television receiver when a video tape recorder is utilized.
In addition, a multiplexed audio signal included in a television signal transmitted from a broadcasting station is formed as a composite signal including an audio signal and a discrimination signal for discrimination of the kind of multiplexing of the audio signal. For example, in a stereo mode an audio signal of one channel comprises an (L+R) signal and an audio signal of the other channel comprises an (L-R) signal as FM modulated and a discrimination signal has AM modulated for representing the stereo mode is also included. The discrimination signal generally has a high frequency, say 55.125 kHz and the current rated recording format makes it impossible to record the same as such in a video tape. More specifically, according to the current rated recording format a video track and an audio track are separately formed and the video track is recorded in a helical scan manner. Therefore, recording of a video signal of a wide range as such is allowed but recording of a discrimination signal in a video track is not allowed. Accordingly, assuming that a discrimination signal is recorded in a video tape, only the way is to record the same in an audio track; however, a discrimination signal is a high-frequency signal, as described above, and the same as such cannot be recorded on an audio track. The reason is that a relative speed of a recording head with respect to an audio track is very low, say as low as 1.3 cm/sec and accordingly the upper limit of the frequency of a recordable signal would be approximately 10 kHz. Therefore, any existing prior art video tape recorders comprise a manual switch separately provided for the purpose of discriminating the kind of an audio signal being recorded, i.e. a stereo mode, a bilingual mode or a monaural mode, in supplying a television signal to a television receiver. However, such conventional video tape recorders adapted for manually discriminating the kind of an audio signal involve another disadvantage that convenience of manual operation is poor.